<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <script src="jquery.min.js"></script>
    <style>
        div {
            width: 100px;
            height: 100px;
            background: red;
        }
        
        .current {
            /* width: 200px;
            height: 200px;
            background: pink; */
            border: 1px solid blue;
        }
        
        .current1 {
            border-radius: 50%;
        }
    </style>
</head>

<body>
    <div></div>
    <script>
        $(function() {
            $('div').addClass('current');
            $('div').addClass('current1'); //添加类名，追加类名
            $('div').click(function() {
                $('div').toggleClass('current1'); //点击切换类名

            })
        })
    </script>
</body>

</html>